Virtually any vehicle is subject to being damaged and requiring repair. Automobiles, commercial vehicles, boats, airplanes, and the like include various exterior and interior panels that may be damaged due to a collision, misuse, or normal wear. It is often less expensive to repair the damaged panel than to replace it. This is especially true for light damage such as scrapes, scratches, chips, mar, and small dents. For heavier damage that affects the structural integrity of the panel, replacement is usually necessary.
For repair of light damage, the spot repair procedure is well known. This repair is done through a multi-step spray painting process to create an invisible repair. Spray painting involves masking off the area to be repaired, pouring and mixing of hazardous materials, e.g., contained in primer and paint topcoats, taking time to flash between spray coats, and energy to dry and cure the final coating. Pouring, mixing, and spraying of the paint results in exposure to spills and volatile organic content (VOC) in the vapors. VOC emission, in recent years, has been restricted by environmental protection laws. Flash off and curing between coats takes time and higher energy costs have driven up the cost for repair shops to cure the paint coat.
The primer coat is especially critical for the spot repair process. It provides a barrier for the substrate for chemical, UV, and heat exposure; it provides a means to adhere the topcoat to the substrate; and it provides sufficient film build to create a smooth, even repair. Application of the primer coat can also be the most time consuming and costly step in the repair process. Depending on the depth or severity of the damage, several coats of body filler and primer-surfacer may be necessary to cover the damage for a smooth repair. This involves spraying multiple coats of primer followed by drying, curing, and sanding. The spraying must be done in a spray booth or other area with proper air circulation for removal of harmful vapor. The primer then must be room or elevated temperature dried to cure the coat so it can be sanded. Once the primer is sanded, it may be determined that another primer coat is necessary to ensure a smooth finish. These multiple steps of spraying, curing, and sanding primer generally involve moving the vehicle around to different areas in a repair shop, where each task can be safely preformed taking up time and space in the shop.
Another issue with spraying primer-surfacer (especially solvent borne primer) for spot repairs is “read through” of the OEM coatings at the junction(s) of the inter-layer(s) exposed during sanding in preparation for the repair. These junctions are vulnerable to solvent entrapment and swelling which creates a bulge that is visible over the refinish top coat. A typical spot repair is illustrated in spot A of FIG. 1. An expanded view of spot A reveals a “bulls-eye” or “contour map” surface, as shown in FIG. 2. This surface is created due to how the damaged area and the surrounding area need to be sanded in preparation for spot repair.
Referring to FIG. 2, the area around the damage is sanded to create a tapered structure so the final appearance of the repair is flush to the existing coatings. Each circle in the bulls-eye in FIG. 2 represents the exposed coating; down to the substrate in the middle and tapered out to the clearcoat on the outside. When primer-surfacer is sprayed over these exposed inter-layers a bulge or read through may not be immediately visible; however, after the primer is flashed and cured, the bulge becomes visible due to swelling at the junction of the inter-layer(s) caused by the solvents in the primer. This read through can telegraph through after the topcoat is sprayed and cured.
Hence, it is an object of the invention to improve efficiency for spot repair compared to convention spraying methods and to reduce or avoid environmental and safety problems associated with conventional primer spraying. It is another object of the invention to reduce or eliminate contour map read through of previous coatings applied during the repair procedure.